SummaryThe optimal treatment and organization of care for people with obesity is one of the greatest challenges facing today's health services. While surgery and pharmacotherapy offer effective treatment options for some people with obesity, behavioral interventions are important to support long‐term behavioral change. However, little is known about the most effective components of behavioral interventions, and this is especially the case for people with complex or severe obesity (i.e. body mass index [BMI] > 35 kg/m2). Accordingly, the current rapid review aimed to identify which behavior change techniques (BCTs) are effective for weight loss in adults with (severe) obesity. A secondary aim was to review the effects of BCTs on dietary behaviors and physical activity, and psychological outcomes, recognizing that behavioral interventions commonly target these. A search of Scopus, Ovid Medline, and Web of Science resulted in 1227 results, with 22 reviews eligible for inclusion. The most commonly reported BCTs were self‐monitoring and goal setting, but these had variable effects on weight in adults with obesity. Combining these BCTs with other self‐regulatory techniques led to increased weight loss. Further, for adults with severe obesity, so‐called ‘nudge’ techniques and self‐regulatory techniques were associated with greater weight loss. Three reviews also found that while self‐monitoring increased physical activity, behavioral commitments increased changes to dietary behaviors. BCTs were not associated with psychological well‐being. The review confirms that behavioral interventions have an impact in weight management, including for individuals with more complex or severe obesity, but highlights the need for further investigation of their use within clinical settings.